Stay-bolt for boilers.



STAY BOLT FOR BOILERS.

PatentedAug. 7', 1917.

' L VVENTOR srns ETHAN I. DODDS, "OF PITTSBURGH, PENNSYLVANIA, ASSIGNOR TO FLANNERY BOLT COMPANY, OF PITTSBURGH, PENNSYLVANIA.

STAY-BOLT FOR BOILERS.

Application filed February 18, 1916.

To all whom it may concern:

Be it known that I, ETHAN I. DoDDs, a citizen of the United States, and a resident of Pittsburgh, in the county of Allegheny and State of Pennsylvania, have invented certain new and useful Improvements in Stay-Bolts for Boilers; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

My improvement relates to an improvement in stay bolts for boilers, and particularly to means for locating fractured stay bolts without removing the caps.

Under the present practice of testing stay bolts, the caps covering the heads of the bolts are removed and the heads tapped with a hammer or other tool, the sound of the tap indicating to the trained ear of the workman the condition of the bolt. This testing is however only done at intervals, and there is no way of indicating or locating any bolts that may be damaged between the test periods.

The object of this invention is to provide means for indicating instantly any bolt that has broken sufficiently to let steam or water under pressure into the tell tale bore or hole in the bolt, and it consists in the parts and combinations of parts as will be more fully explained and pointed out in the claims.

In the accompanying drawings, Figure 1 is a view of a stay bolt of a well known type embodying my invention and Figs. 2 and 3 are modifications of the same.

3 represents the outer sheet of the boiler having a threaded opening for the attachment of the sleeve 4, which is threaded externally to engage the internally threaded opening in the outer sheet. The sleeve 4 projects beyond the outer sheet 3 and this projecting portion is also threaded for the attachment of the cap 5, which is preferably shaped to conform to the curvature of the head 6 of the bolt 7, and is provided centrally with an opening 8 normally closed by a closure that may be ruptured or broken. I prefer to make this closure of soft metal such as lead or copper, but it may be of frangible material that would be broken by impact of the plunger to be hereinafter referred to. This closure, as shown in Fig. 1 is in the form of a lining conforming in shape to the inner face of the cap and hav- Specification of Letters Patent.

Patented Aug. 7, 1917.

Serial No. 79,138.

ing flange 10 at its free edge or periphery which rests on the outer end of the sleeve and forms a sealing gasket for the cap, thus assisting materially in preventing the escape of any water or steam that may get between the head of the bolt and the cap. The sleeve is provided with the curved seat 11 for the head 6 of the bolt, and the bore of the sleeve below or to the inner side of the said seat, is made flaring so as to provide for the free universal movement of the head of the bolt on its seat. The bolt is provided with the tell tale hole or bore 12 which extends through the head and terminates in the body of the bolt at a point beyond the inner face of the outer sheet 3. The outer portion of the telltale bore, or the part thereof within the head of the bolt is preferably enlarged to receive the steel or other hard metal plunger 13, having a pointed outer end 14. This plunger fits snugly within the bore and normally with its pointed end sufficiently removed from the lead or other soft metal lining, to permit the head of the bolt to have free movement without contacting with the lining. In the drawing I have shown the plunger partly projected, but when in its normal position I prefer to have its pointed end wholly within the bore of the head. I also prefer to fill the bore 12 below or behind the plunger, with a grease which will act as a lubricant for the plunger and at the same time prevent any water or steam that may get between the head of the bolt and its cap, from getting into the tell tale bore.

The fracture of flexible stay bolts almost universally occurs at points adjacent the outer sheet as indicated by the horizontal dotted lines in Fig. 1, when the bolt is subjected to undue'strains tending to force it to the position shown in the parallel dotted lines at an angle to the bolt, and when it occurs the steam or water under boiler pressure entering the tell tale bore, forcibly ejects the plunger against the metal lining which is soft enough to be pierced, thus producing an opening through which the steam or water escapes and thus indi cates instantly to the fireman that the stay bolt is broken.

Instead of employing a soft metal lining for the cap, as in Fig. 1, I may use a disk 15 as in Fig. 2. In this construction the cap has a central opening with a shoulder at the bottom of the opening on which the frangible disk 15 is seated, and is locked in place by the ring shaped locking washer 16, which is externally threaded to engage internal threads in the cap.

In the construction shown in Fig. 3 I have dispensed with the sleeve and formed the seat for the bolt head in the outer sheet 3 and have secured the cap 5 directly to the outer sheet by welding, which may be done eijifher by the electric or oXy-acetylene metho s. 7

It is evident that many slight changes might be resorted to in the relative arrangement of parts shown and described without departing from the spirit and scope of my invention. Hence I would have it understood that I do not confine myself to the exact construction and arrangement of parts shown and described except as defined by the scope of the appended claims.

Having fully described my invention what I claim as new and desire to secure by Let ters-Patent, is

1. A stay bolt having a tell tale bore, a cap covering the head of the bolt and provided with an opening, a breakable covering for the opening in said cap, and a plunger within the bore of the bolt and in line with the opening in the cap.

2. A stay bolt having a tell tale bore, a cap covering the head of the bolt and provided with an opening through the same, a soft metal closure for the opening in the cap, and a plunger having a pointed end mounted in the bore of the bolt in line with the opening in the cap.

said bore and adapted to be 3. A stay bolt having a tell tale bore, a breakable covering for the head of the bolt and a plunger within the bore of the bolt and adapted when ejected from said bore to rupture the breakable covering.

4-. A stay bolt structure comprising a sleeve, a cap for the same, having a centrally located opening, a soft metal lining for the cap, forming a closure for the opening in the latter, a bolt having a tell tale bore, and a hard metal plunger located in projected through the lining in the cap.

5. A stay bolt structure comprising a sleeve, a cap having an opening through the same, a soft metal lining for the cap forming a closure for the opening in the latter, a bolt having a tell tale bore and a hard metal plunger located in the said bore, the said plunger having a pointed end to engage and rupture the soft metal covering for the opening in the cap.

6. A stay bolt structure comprising a sleeve, a cap having an opening through the same, a soft metal lining within the cap, the said lining having a peripheral flange seated on the sleeve and forming a seat for the cap, a bolt having a tell tale bore and a plunger mounted in said bore in line with the opening in the cap.

In testimony whereof, I have signed this specification in the presence of two subscribing witnesses.

V ETHAN I. DODDS. Witnesses:

R. S. FERGUSON, S. O. HILL.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, D. G. 

